public function listTopics($project, $optionalArgs = [])
{
$request = new ListTopicsRequest();
$request->setProject($project);
if (isset($optionalArgs['pageSize'])) {
$request->setPageSize($optionalArgs['pageSize']);
}
if (isset($optionalArgs['pageToken'])) {
$request->setPageToken($optionalArgs['pageToken']);
}
$mergedSettings = $this->defaultCallSettings['listTopics']->merge(new CallSettings($optionalArgs));
$callable = ApiCallable::createApiCall($this->publisherStub, 'ListTopics', $mergedSettings, $this->descriptors['listTopics']);
return $callable($request, [], ['call_credentials_callback' => $this->createCredentialsCallback()]);
}